<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>绘制圆形</title>
</head>
<body>
  <canvas id="test" width="800" height="400" style="background: #eee;"></canvas>

  <script>
    /** @type {HTMLCanvasElement} */
    const canvas = document.getElementById('test')
    const context = canvas.getContext('2d')

    context.moveTo(300, 200)
    context.lineTo(200, 200)
    context.lineTo(200, 300)
    
    context.arc(200, 200, 100, 0, Math.PI/2, false)
    // context.stroke()
    context.fillStyle = 'pink'
    context.fill()

  </script>
</body>
</html>